#ifndef _RAY_OBJECT_SPHERE_H
#define _RAY_OBJECT_SPHERE_H

#include <math.h>
#include <stdio.h>

#include "ray_3f.h"
#include "ray_color.h"
#include "ray_object_type.h"
#include "ray_ray.h"
#include "ray_surface.h"


typedef struct ray_object_sphere_t {
	ray_object_type_t	type;
	ray_surface_t		surface;
	ray_3f_t		center;
	float			radius;
} ray_object_sphere_t;


static inline int ray_object_sphere_intersects_ray(ray_object_sphere_t *sphere, ray_ray_t *ray, float *res_distance)
{
	ray_3f_t	v = ray_3f_sub(&ray->origin, &sphere->center);
	float		b = ray_3f_dot(&v, &ray->direction);
	float		disc = (sphere->radius * sphere->radius) - ray_3f_dot(&v, &v) + (b * b);

	if (disc > 0) {
		float	i1, i2;

		disc = sqrtf(disc);

		i1 = b - disc;
		i2 = b + disc;

		if (i2 > 0 && i1 > 0) {
			*res_distance = i1;
			return 1;
		}
	}

	return 0;
}


/* return the normal of the surface at the specified point */
static inline ray_3f_t ray_object_sphere_normal(ray_object_sphere_t *sphere, ray_3f_t *point)
{
	ray_3f_t	normal;
	
	normal = ray_3f_sub(point, &sphere->center);
	normal = ray_3f_div_scalar(&normal, sphere->radius);	/* normalize without the sqrt() */

	return normal;
}


/* return the surface of the sphere @ point */
static inline ray_surface_t ray_object_sphere_surface(ray_object_sphere_t *sphere, ray_3f_t *point)
{
	/* uniform solids for now... */
	return sphere->surface;
}

#endif